Dufour was appointed principal flute of the Chicago Symphony Orchestra in 1999 by Daniel Barenboim.[4] He briefly left in September 2009 to play principal flute with the Los Angeles Philharmonic, though later stated he had joined them on a one-year trial basis and was able to hold positions with both orchestras.[5] He returned to Chicago in January 2010.[6] He joined the Berlin Philharmonic as principal flute in August 2015, replacing the retiring Andreas Blau and sharing the role with Emmanuel Pahud.[7] He left the orchestra in December 2021 at his own request for personal reasons,[8] and was succeeded in May 2022 by Sébastian Jacot.[9]